It works as far as information control is concerned, but fails when it comes to their official reasons for it.
They say they have the arrangement to protect the congregation and to restore the sinner to Jehovah.
Shunning helps neither as it only encourages "sinners" to keep their actions hidden at all costs, and since shunning amounts to emotional blackmail, returning "sinners" likely will be returning, not out of a heartfelt desire to restore their relationship with Jehovah, but instead to reunite with family and friends. This leaves the organization filled with insincere faking JWs.
Also, some who see how nasty their former friends and family really can be and how little they care while they are DF can move them to find unconditional friends on the outside and leave the JW life forever.